1. Field of the Invention
The present invention relates to a delineator and, more specifically, a delineator attached to an object such as a guardrail placed along the road for giving a notice to the driver as to where the road leads to.
2. Description of the Background Art
A delineator has been conventionally known which is attached to a guardrail or a wall surface provided along the road for giving notice to the driver, by reflecting light from a head lamp of a car, for example, to a direction opposite to the incident direction.
FIG. 14 illustrates the function of such a delineator 300. Referring to the figure, delineator 300 includes a mirror finished surface portion (refracting surface) 109, and reflects incident light beam from perpendicular direction 112 of mirror finished surface portion 109 to the opposite direction. The angle within which the incident light beam can be reflected (effective incident angle) is 20.degree. each in left and right directions with respect to perpendicular 112 of the mirror finished surface portion.
FIG. 15 is a cross section showing the mechanism of light reflection of delineator 300. Referring to the figure, delineator 300 has a plurality of reflex reflecting elements 103 therein. Reflex reflecting element 103 is a cubic corner element formed of a transparent acrylic resin, for example. As denoted by the arrows in the figure, the light beam entering through mirror finished surface portion 109 is reflected by the surfaces of reflex reflecting element 103 and output in the direction opposite to the incident direction.
FIG. 16 is a plan view showing such delineators 300 attached on the road 201. In this example, delineators 300 are attached at a T intersection of the road 201. Light beams from the head lamp of a vehicle 200 coming near to the T intersection are reflected by delineators 300. This helps the driver of vehicle 200 to notice the existence of the wall ahead.
Similarly, at a sharp curve of the road 201 such as shown in FIG. 17, the driver notices the curve as the light beams from the headlight of vehicle 200 are reflected.
The conventional delineator, however, suffers from the following problem.
Referring to FIG. 18, if the road 201 curves moderately (or if the road 201 runs straight), the light beams from the headlight of a running vehicle 200 cannot be reflected by delineator 300 even when delineator 300 is attached to the sidewall or a guardrail along the road, as the effective incident angle of the delineator is as narrow as .+-.20.degree., as described with reference to FIG. 14.
A delineator having such a structure as shown in FIG. 19 has been known as a solution of the above described problem, which is capable of reflecting light beams from the vehicle even at a moderate curve or straight road.
Referring to FIG. 19, delineator 300 includes, in addition to reflex reflecting elements 103 arranged parallel to each other on mirror finished surface portion 109, a projection 301 on the side of mirror finished surface portion 109. Because of this projection 301, a light beam proceeding parallel to mirror finished surface portion 109 is reflected by reflex reflecting element 103 through projection 301, and again reflected through projection 301 to the direction opposite to the incident direction. Accordingly, not only the light beams entering perpendicularly but also light beams proceeding parallel to the mirror finished surface portion 109 can effectively be reflected.
However, in such a delineator, not all of the light beams entering from a direction parallel to the mirror finished surface portion 109 are reflected by projection 301, and some of the light beams are transmitted through projection 301. As a result, intensity of the reflected light beams is low.